**Core Concept**
Oral Rehydration Solution (ORS) is designed to replace electrolytes lost during dehydration, particularly in pediatric diarrheal diseases. The potassium concentration in ORS is carefully calibrated to maintain cellular and extracellular fluid balance without causing hyperkalemia or hypokalemia.

**Why the Correct Answer is Right**
The standard WHO-recommended ORS contains **20 mEq/L of potassium**. This concentration is physiologically appropriate—sufficient to support renal function and cellular activity while minimizing the risk of adverse effects. Potassium is essential for maintaining membrane potentials and cardiac function, and its inclusion in ORS helps prevent hypokalemia during rehydration.

**Why Each Wrong Option is Incorrect**
Option A: 30 mEq – This exceeds the recommended level in ORS. High potassium can lead to hyperkalemia, especially in infants and young children with impaired renal function.
Option C: 90 mEq – This is drastically higher and not clinically feasible. It would cause severe hyperkalemia and cardiac arrhythmias.
Option D: 60 mEq – This is also far above the safe and effective range. It represents a dangerous level of potassium that is not used in standard ORS formulations.

**Clinical Pearl / High-Yield Fact**
In pediatric diarrhea, ORS contains **20 mEq/L of potassium**, and the correct ratio of sodium:glucose:potassium is 2:1:0.2. Always remember: **20 mEq of potassium** is the gold standard in ORS—this is a high-yield fact for NEET PG and AIIMS exams.

✓ Correct Answer: B. 20 meq